1. Field of the Invention
This invention relates generally to ground and water based vehicles. It relates particularly to vehicles with reduced aerodynamic drag, in combination with reduced propulsion system wear. It also relates particularly to a method for making a ground or water based vehicle with reduced aerodynamic drag in combination with reduced propulsion system wear.
2. Description of the Related Art
Inventions related to the improvement in drag reduction for trucks, trains, and other ground based vehicles have been in existence for fifty years or more. Several patents have been issued for inventions which reduce vehicle drag by adding aerodynamically shaped hardware to the existing vehicle structure. Some such devices are semi-spherical in geometry, some are conical, some angular, some inflatable, some rigid, some comprised of hinged panels, some fabricated from solid material, and some utilizing porous surfaces. Other drag reduction systems utilize powered suction or blowing to control boundary layer aerodynamic effects along the surface of the vehicle. Some inventions utilize a combination of the drag reduction techniques above, and patents exist for other methods as well.
Likewise, ground effects or hovercraft technology has been in existence for many years. Ground effects vehicles historically have utilized a cushion of air to completely lift the vehicle off the ground, rail, or water. Jet or propeller driven thrust is typically used to propel the vehicle, and some form of rudder, or mechanical channel or rail, is used for steering.
Studies have shown that suction or blowing powered drag reduction technology can be effective, reducing aerodynamic drag on large vehicles by as much as thirty-five percent, and thereby significantly improving fuel economy. Such systems are often wasteful in other ways, however. For example, a considerable amount of energy is expended by such systems, arguably enough to nullify the savings produced by the drag reduction. As a result, the drag reduction may come at a cost which makes implementation prohibitive.
Similarly, ground effects vehicles, e.g. hovercraft, consume great amounts of energy in order to lift the vehicle entirely off the ground, water, or rail. They can be both expensive and noisy to operate.
It would be beneficial, therefore, to provide an invention which not only reduces aerodynamic drag on a vehicle, but also utilizes the energy expended by the drag reduction system to provide partial lift on the vehicle. The energy required for lift then becomes free of charge. The benefits of drag reduction are still realized, plus added benefits of partial lift are appreciated. Such an invention is of particular value at a time when fuel costs are escalating at an unprecedented rate, and at a time when ecology, recycling, noise pollution, and other environmental concerns are highly significant.
It is therefore an object of the present invention to provide a system which reduces the drag on a vehicle, then makes additional beneficial use of the energy expended and the air collected by the drag reduction system.
It is a related object of the invention to use the energy and air supplied by the drag reduction hardware to provide a system which decreases the wear on a vehicle""s propulsion equipment.
It is a further object of the invention to provide a system which decreases the wear on some surfaces over which a vehicle may travel.
These and other objects, features, and advantages of the present invention will become apparent to those skilled in the art through the subsequent descriptions, drawings, and claims.
In accordance with these and other objects, the present invention provides a novel combination of existing aerodynamic drag reduction technology and existing ground effects technology. The novel combination results in a unique and efficient system which provides the benefits of both previous technologies, as well as some benefits which were previously unavailable. The invention is both the vehicle which combines drag reduction and ground effects technology to accomplish the desired benefits, and the method for combining drag reduction and ground effects technology for the same purpose.
In an embodiment of the present invention, porous panels at the trailing end of a vehicle are used to improve the vehicle""s aerodynamic shape, thus reducing aerodynamic drag on the vehicle. Aerodynamic drag is further reduced by suction through the surfaces of the porous panels, which provides control of the turbulent boundary layer flow over the panels.
Normally in prior art drag reduction systems, the air suctioned off the boundary layer is exhausted to the environment, serving no further purpose. The present invention recycles the suctioned air, however, and also makes more efficient use of the energy expended by the suction devices, by pumping the suctioned air to an air cushion underneath the vehicle instead of releasing the air to the atmosphere.
The air cushion partially lifts the vehicle, reducing the loading it imparts to its structure and propulsion system (e.g. tires, axles, treads, propellers, etc.) by a desired fractional amount. The reduced loading on the vehicle""s propulsion system not only reduces the wear on vehicle hardware, but also reduces the wear on surfaces with which the vehicle""s propulsion system may come in contact. The reduced loading also reduces friction between the propulsion system and the surface over which the vehicle travels, potentially further reducing drag on the vehicle. Additionally, the fact that only partial lift is required decreases the amount of power necessary to provide lift, and significantly reduces the noise level produced by the system.
Overall benefits of the present invention include savings in fuel costs, savings in vehicle maintenance and part replacement costs, and savings in road or rail maintenance, or repair to other surfaces contacted by the moving vehicle.